BS84B08A-3 Datasheet, PDF (40/123 Pages) Holtek Semiconductor Inc – A/D Type Touch Key MCU

BS84B08A-3/BS84C12A-3
A/D Type Touch Key MCU
Entering the IDLE1 Mode
There is only one way for the device to enter the IDLE1 Mode and that is to execute the “HALT”
instruction in the application program with the IDLEN bit in SMOD register equal to “1” and the
FSYSON bit in CTRL register equal to “1”. When this instruction is executed under the conditions
described above, the following will occur:
• The system clock and the low frequency fSUB will be on and the application program will stop at
the “HALT” instruction.
• The Data Memory contents and registers will maintain their present condition.
• The WDT will be cleared and resume counting.
• The I/O ports will maintain their present conditions.
• In the status register, the Power Down flag, PDF, will be set and the Watchdog time-out flag, TO,
will be cleared.
N O R M A L M ode
C K S 2 ~ C K S 0 = 00xB &
H LC LK = 0
S LO W M ode
W D T is o n
ID L E N = 0
H A L T in s tr u c tio n is e x e c u te d
S LE E P M ode
ID L E N = 1 , F S Y S O N = 0
H A L T in s tr u c tio n is e x e c u te d
ID E L 0 M o d e
ID L E N = 1 , F S Y S O N = 1
H A L T in s tr u c tio n is e x e c u te d
ID L E 1 M o d e
S LO W M ode
C K S 2~C K S 0¹000B ,001B
as H LC LK =0 orH LC LK =1
N O R M A L M ode
W D T is o n , ID L E N = 0
H A L T in s tr u c tio n is e x e c u te d
S LE E P M ode
ID L E N = 1 , F S Y S O N = 0
H A L T in s tr u c tio n is e x e c u te d
ID L E 0 M o d e
ID L E N = 1 , F S Y S O N = 1
H A L T in s tr u c tio n is e x e c u te d
ID L E 1 M o d e
Standby Current Considerations
As the main reason for entering the SLEEP or IDLE Mode is to keep the current consumption of the
device to as low a value as possible, perhaps only in the order of several micro-amps except in the
IDLE1 Mode, there are other considerations which must also be taken into account by the circuit
designer if the power consumption is to be minimised. Special attention must be made to the I/O pins
on the device. All high-impedance input pins must be connected to either a fixed high or low level as
any floating input pins could create internal oscillations and result in increased current consumption.
This also applies to devices which have different package types, as there may be unbonded pins.
These must either be setup as outputs or if setup as inputs must have pull-high resistors connected.
Care must also be taken with the loads, which are connected to I/O pins, which are setup as
outputs. These should be placed in a condition in which minimum current is drawn or connected
only to external circuits that do not draw current, such as other CMOS inputs. In the IDLE1 Mode
the system oscillator is on, if the system oscillator is from the high speed system oscillator, the
additional standby current will also be perhaps in the order of several hundred micro-amps.
Rev. 1.00
40
May 02, 2013